JP2005147648A - Water tube boiler - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To minimize a pressure loss while realizing high boiler efficiency, and to uniform a heat load of a water tube in a body of a water tube boiler. <P>SOLUTION: The water tube boiler is provided with an annular first water tube row 4 composed of a plurality of first water tubes 3, 3, etc., and formed with gaps 5, 5, etc. between adjacent first water tubes 3 throughout a predetermined range, a combustion chamber 9 formed in an inner side of the first water tube row 4, a wall member 11 provided in an outer side of the first water tube row 4, and a gas passage 13 formed by the first water tube row 4 and the wall member 11. A passage cross sectional area of the predetermined range of the gas passage 13 is set so as to suppress increase of a flow velocity of gas. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a can structure of a water tube boiler such as a once-through boiler, a natural circulation water tube boiler, or a forced circulation water tube boiler.

  In the can structure of the water tube boiler, a plurality of water tubes are annularly arranged to form an inner water tube row, a combustion chamber is formed inside the inner water tube row, and a plurality of water tubes are further provided outside the inner water tube row. Some water tubes are annularly arranged to form an outer water tube row, and a gas flow path is formed by both water tube rows. Radiation heat transfer is mainly performed in the combustion chamber, and convection heat transfer is mainly performed in the gas flow path.

  In the water pipe boiler, in order to improve boiler efficiency, measures are taken to increase the heat transfer area by providing heat transfer fins in each water pipe. Specifically, horizontal fin-shaped heat transfer fins are provided in multiple stages on the heat transfer surface on the gas flow path side in both the water tube rows to improve boiler efficiency (for example, Japanese Patent Publication No. 6-13921). (See U.S. Pat. No. 4,825,813)).

  As an advantage of this structure, there is an advantage that the heat transfer area is increased by the heat transfer fins to improve the boiler efficiency, and the boiler efficiency is less likely to be lowered due to a manufacturing error. However, on the other hand, there is a problem that the pressure loss is large, and it is necessary to use a large blower. In addition, the inflow of gas from the combustion chamber to the gas flow path is performed through an opening provided in the inner water pipe row. When there is only one opening, the area around the opening is There was the subject that the heat load of each water pipe became high.

Japanese Patent Publication No. 6-13921 (US Pat. No. 4,825,813)

  The problem to be solved by the present invention is to achieve a high boiler efficiency in the can of a water tube boiler while keeping the pressure loss low and making the heat load of the water tube uniform.

  This invention was made in order to solve the said subject, and invention of Claim 1 is comprised by the some 1st water pipe, and a clearance gap is formed over the predetermined range between each said 1st water pipe adjacent. An annular first water tube row, a combustion chamber formed inside the first water tube row, a wall member provided outside the first water tube row, and the first water tube row and the wall member And a gas cross-sectional area of the predetermined range in the gas flow channel is set so as to suppress an increase in gas flow velocity.

  The invention according to claim 2 is constituted by a plurality of first water pipes, an annular first water pipe row in which a gap is formed over a predetermined range between the adjacent first water pipes, and an inner side of the first water pipe row A combustion chamber formed on the outside, a wall member provided outside the first water pipe row, and a gas flow path formed by the first water pipe row and the wall member, The channel cross-sectional area of the predetermined range is gradually increased toward the downstream side in the gas flow direction.

  The invention described in claim 3 is characterized in that each of the gaps is made smaller as the gap is located downstream in the gas flow direction in the gas flow path.

  Furthermore, the invention described in claim 4 is characterized in that the wall member is an annular second water pipe row constituted by a plurality of second water pipes.

  According to the present invention, a sufficient amount of heat transfer can be obtained in the gas flow path, and an appropriate gas flow rate at which the pressure loss does not become so large can be maintained, and both high boiler efficiency and low pressure loss are achieved. can do. That is, the pressure loss can be kept low while realizing high boiler efficiency. Moreover, since gas flows into the gas flow path from a plurality of the gaps, the heat transfer amount is distributed to the first water pipes, and the heat load of the first water pipes can be made uniform.

  Next, an embodiment of the present invention will be described. The present invention is implemented as a multi-tube water tube boiler, and is applied to a heat medium boiler that heats a heat medium in addition to a steam boiler and a hot water boiler.

  First, a first embodiment of the present invention will be described. In the can of the water tube boiler according to the present invention, an annular first water tube row is formed by a plurality of first water tubes, and a combustion chamber is formed inside the first water tube row. In the first water pipe row, a gap is formed over a predetermined range between the adjacent first water pipes. In other words, the first water pipe row is constituted by the gap holding part in the predetermined range and the remaining water pipe wall part. The water pipe wall portion is not formed with the gaps, and is configured by closely contacting the first water pipes or by connecting the first water pipes with a first connection fin. A cylindrical wall member is provided outside the first water tube row, and a gas flow path is formed by the first water tube row and the wall member. The gas flow path and the combustion chamber communicate with each other through the gaps. The wall member is provided with an opening at a position facing the water pipe wall, and the gas flowing through the gas flow path is discharged to the outside through the opening.

  In addition, the flow passage cross-sectional area of the predetermined range (that is, the portion formed by the gap holding portion and the wall member in the gas flow passage) of the gas flow passage is the amount of gas flowing through the gas flow passage. It is set to suppress the increase in flow velocity. Specifically, since the flow rate of the gas flowing through the gas flow path is increased by the merge of the gas from the gaps, the cross-sectional area of the flow path is gradually increased toward the downstream side in the gas flow direction. It is said. With this configuration, the flow rate of the gas flowing through the predetermined range in the gas flow path can be made almost constant, a sufficient amount of heat transfer can be obtained, and an appropriate gas flow rate that does not increase pressure loss is maintained. can do. Therefore, both high boiler efficiency (heat recovery rate) and low pressure loss can be achieved. In order to make the gas flow rate substantially constant, the gas flow rate is maintained within a predetermined range, and if it is within this predetermined range, the one that slightly increases is included.

Here, in the predetermined range of the gas flow path, heat transfer from the gas to the heated fluid flowing in the first water pipes is performed, so that the temperature of the gas is lowered, and the gas volume is reduced by the accompanying volume reduction. Although the flow rate decreases, the gas flow rate increases as a whole because the increase amount of the gas flow rate due to the merge is larger. Therefore, the flow path cross-sectional area is set in consideration of the volume decrease due to the temperature decrease. On the other hand, in the gas flow path, outside the predetermined range (that is, the portion formed by the water pipe wall portion and the wall member in the gas flow path), there is no gas merging, and the gas temperature due to heat transfer As the flow rate decreases, the gas flow rate decreases. Thus, the cross-sectional area of the flow path is gradually reduced toward the downstream side in the gas flow direction. As a result, a sufficient amount of heat transfer can be obtained even outside the predetermined range in the gas flow path, and an appropriate gas flow rate at which the pressure loss does not become so large can be maintained. Further, depending on the implementation, for example, when the length outside the predetermined range of the gas flow path is short, the cross-sectional area of the flow path may not be reduced.

  Moreover, the said clearance holding part is provided over the range of 140 degree | times -320 degree | times in the center angle of said 1st water pipe row | line | column, Preferably it is provided over the range of about 180 degree | times. The gaps (specifically, the widths of the gaps) can be set evenly, but since the gaps closer to the downstream side are closer to the opening, the gas easily flows and the gas flow rate is larger. Therefore, the gaps are set to be smaller toward the downstream side of the gas flow path in the gas flow direction. With this configuration, it is possible to suppress the deviation of the gas flow rate in each of the gaps and make the gas flow rate substantially uniform in each of the gaps. Here, the width of each gap is set in the range of 0.5 to 3 mm when the fuel is gas fuel, and when the fuel is oil fuel, 1.5 to The range is set to 8mm.

  Hereinafter, the operation of the above configuration will be described. Gases generated by combustion of fuel in the combustion chamber (including gases in the combustion reaction and gases in which the combustion reaction has been completed) flow into the gas flow path from the gaps, and merge in the gas flow path. After flowing through the gas flow path, the gas is discharged from the opening to the outside. In the course of this flow, heat transfer from the gas to the heated fluid in each first water pipe is performed, radiant heat transfer is mainly performed in the combustion chamber, and in each gap and the gas flow path, Convection heat transfer is mainly performed. Further, when the gas passes through the gaps, the gas in the combustion reaction comes into contact with the first water pipes and is cooled, and the combustion temperature is lowered. Therefore, the generation of thermal NOx is suppressed, and the NOx emission amount is reduced. Reduced.

  In the above-described configuration, by setting each gap to be smaller as the downstream side becomes smaller, the gap on the upstream side becomes relatively large, and a predetermined amount of gas flows out from the gap on the upstream side. The gas flow rate is almost uniform. Therefore, the heat load of each first water pipe in the gap holding part can be made uniform. If there is a bias in the heat load, the higher the heat load, the more the scale is a heat transfer inhibiting substance on the inner surface of the first water pipe, and overheating tends to occur, but this problem is solved by making the heat load uniform. can do.

  In addition, the gas flow velocity is substantially constant corresponding to the increase in the gas flow rate due to the merging of the gas from the respective gaps by the configuration in which the cross-sectional area of the predetermined range is gradually increased in the gas flow channel. Therefore, a sufficient amount of heat transfer can be obtained in the predetermined range of the gas flow path, and an appropriate gas flow rate at which the pressure loss does not become so large can be maintained, and high boiler efficiency and low pressure loss can be achieved. It can be compatible. That is, the pressure loss can be kept low while realizing high boiler efficiency. Since high boiler efficiency can be realized, fuel consumption can be reduced and energy saving can be realized. In addition, since a low pressure loss can be realized, a small fan can be used as a blower for supplying combustion air, and power consumption can be reduced.

  Here, in setting the width of each gap and the cross-sectional area of the gas flow path, the gas from each gap flows around the first water pipe in relation to the gas flow velocity of the gas flow path. The value is set so as to flow along the surface (so as to obtain a so-called Coanda effect). By doing so, the amount of heat transfer from the gas to the first water pipes forming the gaps increases.

Next, a second embodiment of the present invention will be described. In the second embodiment, an annular second water pipe row is provided as the wall member. That is, the second water pipe row constituted by a plurality of second water pipes is arranged outside the first water pipe row, and the gas flow path is formed by both the water pipe rows. Similar to the first embodiment, the gas flow path and the combustion chamber communicate with each other through the gaps. In addition, the opening is provided at a position facing the water pipe wall in the second water pipe row, and the gas flow path is configured to extend from the gaps to the opening.

  Here, a modification of the second embodiment will be described. In the second embodiment, a configuration may be adopted in which a predetermined number of water pipe rows are further provided outside the second water pipe row, depending on the implementation.

  The specific configuration of each gap and the gas flow path is the same as that of the first embodiment, and thus detailed description thereof is omitted.

  Since the second embodiment is configured as described above, the same operational effects as those of the first embodiment can be obtained.

  By the way, each of the annular water tube rows in both the embodiments can be circular or oval. Moreover, it can be set as the structure which provided the horizontal heat-transfer fin in multiple stages at the said gas flow path side in each said water pipe row | line | column. By doing so, a heat transfer area increases and the amount of heat transfer further increases. Furthermore, in each said 1st water pipe which forms each said clearance gap, the cross-sectional shape can also be made into an ellipse shape or a barrel shape besides circular shape. That is, the part which forms each said clearance gap in each said 1st water pipe is made into planar shape, The length of the gas flow direction of each said clearance gap is lengthened, and the heat transfer amount in each said clearance gap is increased.

  Hereinafter, specific embodiments of the present invention will be described in detail with reference to the drawings. First, the first embodiment will be described with reference to FIGS. The first embodiment is an embodiment in which the present invention is applied to a multitubular once-through boiler.

  The boiler body includes an upper header 1 and a lower header 2 arranged at a predetermined distance. Between these upper header 1 and lower header 2, a plurality of first water pipes 3, 3,. Each of these first water pipes 3 forms an annular first water pipe row 4, and the upper and lower ends of each of the first water pipes 3 are connected to the upper header 1 and the lower header 2, respectively. The first water pipe row 4 includes a gap holding portion 6 in which gaps 5, 5,... Are respectively formed between the adjacent first water pipes 3, and the first connection fins 7, 7, It is comprised by the water pipe wall part 8 connected and comprised by .... In the first embodiment, the gap holding portion 6 and the water pipe wall portion 8 are set to about ½ each.

  A combustion chamber 9 is formed inside the first water pipe row 4. A burner 10 is attached above the combustion chamber 9. The burner 10 is inserted from the inner central part of the upper header 1 toward the combustion chamber 9. The burner 10 is connected to a blower (not shown) for supplying combustion air.

  A cylindrical wall member 11 is provided outside the first water pipe row 4. The upper and lower ends of the wall member 11 are connected to the upper header 1 and the lower header 2, respectively. The wall member 11 includes an opening 12 in a part thereof. The opening 12 is provided at a position on the opposite side of the gap holding part 6 by about 180 degrees, that is, at a position facing the water pipe wall 8.

  The first water pipe row 4 and the wall member 11 form gas flow paths 13 and 13 extending from the gaps 5 to the opening 12. Both gas flow paths 13 communicate with the combustion chamber 9 via the gaps 5 and communicate with the flue 14 via the opening 12. Therefore, the gas from each gap 5 flows through both the gas flow paths 13, merges at the opening 12, and is discharged from the flue 14 to the outside.

  A heat insulating material 15 is provided outside the wall member 11, and a can cover 16 is provided outside the wall member 11.

  Now, the configurations of the gaps 5 and the gas passages 13 will be described more specifically. In the following description, the gas flow paths 13 are substantially symmetrical as flow paths from the gaps 5 to the openings 12, and therefore, one gas flow path 13 will be described.

  First, each gap 5 will be specifically described. The width of each gap 5 is set to be smaller toward the downstream side of the gas flow path 13 in the gas flow direction. This is because the gas gap tends to flow and the gas flow rate tends to increase because the gap 5 on the downstream side is closer to the opening 12, and the deviation of the gas flow rate in each gap 5 is suppressed. With this configuration, the gas flow rate in each gap 5 can be made substantially uniform, and the heat load of each first water pipe 3 in the gap holding portion 6 can be made almost uniform. In this first embodiment, the width of the gap 5 on the most upstream side is 6 mm, and the width is 4 mm, 4 mm, 4 mm, 3 mm, 3 mm, 3 mm, 2 mm, 2 mm, and 2 mm in order toward the downstream side.

  Next, the gas flow path 13 will be specifically described. The flow path cross-sectional area of the predetermined range in the gas flow path 13 (that is, the portion formed by the gap holding portion 6 and the wall member 11 in the gas flow path 13) is the downstream side in the gas flow direction. The structure is gradually increased toward. That is, the distance A (see FIG. 3) between the outer peripheral surface of each first water pipe 3 and the inner peripheral surface of the wall member 11 gradually increases toward the downstream side in the gas flow direction. Moreover, in this 1st Example, the diameter of each said 1st water pipe 3 is the same, The distance B (refer FIG. 3) of the center of each said 1st water pipe 3 and the internal peripheral surface of the said wall member 11 ) Also gradually increases toward the downstream side in the gas flow direction.

  In the gas flow path 13, the flow rate of the gas flowing through the gas flow path 13 increases due to the confluence of the gas from the gaps 5. In addition, the gas flow rate decreases due to heat transfer, and the gas flow rate decreases due to the gas volume reduction associated therewith. However, since the amount of increase in gas flow rate due to merging is larger, the gas flow rate generally increases. Therefore, by adopting a configuration in which the flow path cross-sectional area is gradually increased, the flow velocity of the gas flowing through the predetermined range in the gas flow path 13 can be made substantially constant, and a sufficient amount of heat transfer can be obtained. It is possible to maintain an appropriate gas flow rate in which the pressure loss is not so great. Therefore, both high boiler efficiency and low pressure loss can be achieved.

  Here, the configuration in which the flow path cross-sectional area is gradually increased is realized, for example, by arranging the first water pipe row 4 and the wall member 11 so as to be eccentric from each other. That is, the first water pipe row 4 is eccentric to the side opposite to the opening 12 with respect to the wall member 11, or the wall member 11 is moved toward the opening 12 with respect to the first water pipe row 4. Make it eccentric. In the first embodiment, the latter eccentric structure is adopted.

  Furthermore, the heat transfer surface structure on the gas flow path 13 side in the first water pipe row 4 will be specifically described. In the first water pipe row 4, horizontal fin-shaped first heat transfer fins 17, 17,... Are provided in multiple stages on the first water pipes 3 in the gap holding part 6, and the water pipe wall 8 Each of the first water pipes 3 is provided with multi-stage second fins 18, 18,. Each of these heat transfer fins 17 and 18 protrudes from the peripheral surface of each of the first water pipes 3 toward the gas flow path 13 and is provided substantially horizontally, so that the amount of heat transfer is increased while increasing the amount of heat transfer. An increase in the distribution resistance can be suppressed. And according to the temperature of the gas which contacts, the protrusion height of each said 2nd heat transfer fin 18 is made higher than the protrusion height of each said 1st heat transfer fin 17. FIG. Thus, the first water pipe row 4 has a two-stage heat transfer surface structure.

  The effect | action is demonstrated in the boiler of the above structure. When the burner 10 is operated, a combustion reaction is performed in the combustion chamber 9, and the gas generated by the combustion reaction (including the gas during the combustion reaction and the gas for which the combustion reaction has been completed) passes through the gaps 5. It flows into the gas flow path 13. The gas merged in the gas flow path 13 flows through the gas flow path 13 and is discharged to the outside as exhaust gas from the opening 12 through the flue 14. In the course of this flow, heat transfer from the gas to the fluid to be heated in each first water pipe 3 is performed, and in the combustion chamber 9, radiant heat transfer is mainly performed, and each gap 5 and each gas In the flow path 13, convective heat transfer is mainly performed. And the to-be-heated fluid in each said 1st water pipe 3 rises, being heated, and is taken out from the said upper header 1 as a vapor | steam.

  In each of the gaps 5, the width of each of the gaps 5 is set to be smaller toward the downstream side, so that a predetermined amount of gas flows out of the gaps 5 on the upstream side, and the gaps 5 are substantially uniform. Gas flow rate. Therefore, the heat load of each first water pipe 3 in the gap holding part 6 can be made uniform. If there is a bias in the heat load, the higher the heat load, the higher the heat load, the more the scale, which is a heat transfer inhibiting substance, will adhere to the inner surface of the first water pipe 3, but this problem will be solved by making the heat load uniform. Can be resolved. Further, when the gas passes through the gaps 5, the gas in the combustion reaction comes into contact with the first water pipes 3 and is cooled to reduce the combustion temperature, so that the generation of thermal NOx is suppressed and NOx is discharged. The amount is reduced.

  Further, the gas flow rate is substantially constant corresponding to the increase in the gas flow rate due to the merging of the gas from the gaps 5 by the configuration in which the cross-sectional area of the predetermined range in the gas flow channel 13 is gradually increased. Become. Accordingly, a sufficient amount of heat transfer can be obtained in the predetermined range of the gas flow path 13, and an appropriate gas flow rate at which the pressure loss does not become so large can be maintained, and both high boiler efficiency and low pressure loss are achieved. can do. Since high boiler efficiency can be realized, fuel consumption can be reduced and energy saving can be realized. Moreover, since a pressure loss can be reduced, a small thing can be used as the said air blower, and electric power consumption can be reduced significantly.

  Next, a second embodiment will be described with reference to FIGS. The second embodiment is an embodiment in which the present invention is applied to a multi-tube type once-through boiler as in the first embodiment. Here, the same components as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  In the second embodiment, an annular second water pipe row 19 is disposed as the wall member 11. That is, the second water pipe row 19 is arranged outside the first water pipe row 4 to form a double water pipe row structure. The first water pipe row 4 has the same configuration as that of the first embodiment, and the gap holding part 6 and the water pipe wall part 8 are set to about ½ each.

  The second water pipe row 19 is formed by arranging a plurality of second water pipes 20 in an annular shape, and each of the second water pipes 20 is connected by second connection fins 21, 21,. The upper and lower ends of each second water pipe 20 are connected to the upper header 1 and the lower header 2, respectively. The second water pipe row 19 is provided with the opening 12 in a part thereof. The opening 12 is provided at a position on the opposite side of the gap holding portion 6 by about 180 degrees, that is, a position facing the water pipe wall 8. Moreover, each said 1st water pipe 3 and each said 2nd water pipe 20 are arrange | positioned in the state shifted by the half pitch at a circumferential direction.

The first water pipe row 4 and the second water pipe row 19 form the gas flow paths 13 and 13 extending from the gaps 5 to the opening 12. Both the gas flow paths 13 communicate with the combustion chamber 9 via the gaps 5 and communicate with the flue 14 via the opening 12. Therefore, the gas from each gap 5 flows through both the gas flow paths 13, merges at the opening 12, and is discharged from the flue 14 to the outside.

  The heat insulating material 15 is provided outside the second water pipe row 19, and the can cover 16 is provided outside the second water pipe row 19.

  The specific configurations of the gaps 5 and the gas flow paths 13 are the same as in the first embodiment, and are as follows. In the following description, the gas flow paths 13 are substantially symmetrical as flow paths from the gaps 5 to the openings 12, and therefore, one gas flow path 13 will be described.

  First, each gap 5 will be specifically described. The width of each gap 5 is set to be smaller toward the downstream side of the gas flow path 13 in the gas flow direction. This is because the gas gap tends to flow and the gas flow rate tends to increase because the gap 5 on the downstream side is closer to the opening 12, and the deviation of the gas flow rate in each gap 5 is suppressed. With this configuration, the gas flow rate in each gap 5 can be made substantially uniform, and the heat load of each first water pipe 3 in the gap holding portion 6 can be made almost uniform. Also in the second embodiment, the width of the gap 5 on the most upstream side is 6 mm, and the width is 4 mm, 4 mm, 4 mm, 3 mm, 3 mm, 3 mm, 2 mm, 2 mm, and 2 mm in order toward the downstream side.

  Next, the gas flow path 13 will be specifically described. In the gas flow path 13, the flow path cross-sectional area of the predetermined range is gradually increased toward the downstream side in the gas flow direction. That is, the distance C between the outer peripheral surface of each first water pipe 3 and the inner side of the second water pipe row 19 (arc line X (indicated by a two-dot chain line) in contact with the outer peripheral surface of each second water pipe 20) (see FIG. 6). ) Gradually increase toward the downstream side in the gas flow direction. In the second embodiment, the diameters of the water pipes 3 and 20 are the same, and the arc Y that connects the centers of the second water pipes 20 to the second connection fins 21 (indicated by a one-dot chain line). The distance D (see FIG. 6) between the center of each first water pipe 3 and the inner wall surface of each second connection fin 21 is also gradually increased toward the downstream side in the gas flow direction. ing.

  In the gas flow path 13, the flow rate of the gas flowing through the gas flow path 13 increases due to the confluence of the gas from the gaps 5. In addition, the gas flow rate decreases due to heat transfer, and the gas flow rate decreases due to the gas volume reduction associated therewith. However, since the amount of increase in gas flow rate due to merging is larger, the gas flow rate generally increases. Therefore, by adopting a configuration in which the flow path cross-sectional area is gradually increased, the flow velocity of the gas flowing through the predetermined range in the gas flow path 13 can be made substantially constant, and a sufficient amount of heat transfer can be obtained. It is possible to maintain an appropriate gas flow rate in which the pressure loss is not so great. Therefore, both high boiler efficiency and low pressure loss can be achieved.

  Here, the configuration in which the flow path cross-sectional area is gradually increased is realized, for example, by arranging the water pipe rows 4 and 19 so as to be eccentric from each other. That is, the first water pipe row 4 is eccentric to the side opposite to the opening 12 with respect to the second water pipe row 19, or the second water pipe row 19 is opened with respect to the first water pipe row 4. Eccentric toward the part 12 side. In the second embodiment, the latter eccentric structure is adopted.

Furthermore, the heat transfer surface structure on the gas flow path 13 side in both the water pipe rows 4 and 19 will be specifically described. In the first water pipe row 4, as in the first embodiment, each first heat transfer fin 17 having a horizontal fin shape is provided in multiple stages on each first water pipe 3 in the gap holding portion 6, Each said 1st water pipe 3 in the said water pipe wall part 8 is provided with each said 2nd heat transfer fin 18 of a horizontal fin shape in multiple stages. Each of the heat transfer fins 17 and 18 protrudes from the peripheral surface of each of the first water pipes 3 toward the gas flow path 13 and is provided substantially horizontally. Therefore, while increasing the heat transfer amount, An increase in distribution resistance can be suppressed. And according to the temperature of the gas which contacts, the protrusion height of each said 2nd heat transfer fin 18 is made higher than the protrusion height of each said 1st heat transfer fin 17. FIG. Thus, the first water pipe row 4 has a two-stage heat transfer surface structure.

  Moreover, in the said 2nd water pipe row | line | column 19, the heat-transfer surface which consists of the said 2nd water pipe 20 which is not provided with the heat-transfer fin in order from the upstream, the horizontal fin-shaped 3rd heat-transfer fins 22, 22, ... are multistage. Are provided with a heat transfer surface comprising the second water pipe 20 provided in the second water pipe 20 provided in multiple stages with horizontal fin-shaped fourth heat transfer fins 23, 23,. It has a three-stage heat transfer surface structure. Each of these heat transfer fins 22 and 23 protrudes from the peripheral surface of each of the second water pipes 20 toward the gas flow path 13 and is provided substantially horizontally, so that the amount of heat transfer is increased while increasing the amount of heat transfer. An increase in the distribution resistance can be suppressed. And according to the temperature of the gas which contacts, the protrusion height of each said 4th heat transfer fin 23 is made higher than the protrusion height of each said 3rd heat transfer fin 22. FIG.

  The effect | action is demonstrated in the boiler of the above structure. When the burner 10 is operated, a combustion reaction is performed in the combustion chamber 9, and the gas generated by the combustion reaction (including the gas during the combustion reaction and the gas for which the combustion reaction has been completed) passes through the gaps 5. It flows into the gas flow path 13. The gas merged in the gas flow path 13 flows through the gas flow path 13 and is discharged to the outside as exhaust gas from the opening 12 through the flue 14. In the course of this flow, heat is transferred from the gas to the heated fluid in each of the water pipes 3 and 20, and radiant heat transfer is mainly performed in the combustion chamber 9, and the gaps 5 and the gas are transferred. In the flow path 13, convective heat transfer is mainly performed. Then, the heated fluid in each of the water pipes 3 and 20 rises while being heated and is taken out from the upper header 1 as steam.

  In each of the gaps 5, the width of each of the gaps 5 is set to be smaller toward the downstream side, so that a predetermined amount of gas flows out of the gaps 5 on the upstream side, and the gaps 5 are substantially uniform. Gas flow rate. Therefore, the heat load of each first water pipe 3 in the gap holding part 6 can be made uniform. If there is a bias in the heat load, the higher the heat load, the higher the heat load, the more the scale, which is a heat transfer inhibiting substance, will adhere to the inner surface of the first water pipe 3, but this problem will be solved by making the heat load uniform. Can be resolved. Further, when the gas passes through the gaps 5, the gas in the combustion reaction comes into contact with the first water pipes 3 and is cooled to reduce the combustion temperature, so that the generation of thermal NOx is suppressed and NOx is discharged. The amount is reduced.

  Further, the gas flow rate is substantially constant corresponding to the increase in the gas flow rate due to the merging of the gas from the gaps 5 by the configuration in which the cross-sectional area of the predetermined range in the gas flow channel 13 is gradually increased. Become. Accordingly, a sufficient amount of heat transfer can be obtained in the predetermined range of the gas flow path 13, and an appropriate gas flow rate at which the pressure loss does not become so large can be maintained, and both high boiler efficiency and low pressure loss are achieved. can do. In this second embodiment, the gas flow rate in the gas flow path 13 is about 20 m / s, the pressure loss of the entire can body is about 300 mmAq, and the boiler efficiency is about 90%. Since high boiler efficiency can be realized, fuel consumption can be reduced and energy saving can be realized. In addition, the pressure loss is reduced by about 40% compared to the conventional one, and a small fan can be used as the blower, so that power consumption can be greatly reduced.

In each of the above-described embodiments, the can body in which the gas from each gap 5 flows through both the gas flow paths 13 has been described. This invention is described in FIGS. 1 and 2 of US Pat. No. 4,257,358, for example. As can be seen, the present invention can also be applied to a can body in which gas flows in one direction so as to make one round of the gas flow path 13.

It is longitudinal cross-sectional explanatory drawing of the 1st Example in this invention. It is transverse cross-sectional explanatory drawing which follows the II-II line | wire of FIG. FIG. 3 is an explanatory cross-sectional view showing an enlarged main part of FIG. 2. It is longitudinal cross-sectional explanatory drawing of the 2nd Example in this invention. It is a cross-sectional explanatory drawing along the VV line of FIG. FIG. 6 is an explanatory cross-sectional view showing an enlarged main part of FIG. 5.

Explanation of symbols

Reference Signs List 3 First water pipe 4 First water pipe row 5 Clearance 9 Combustion chamber 11 Wall member 13 Gas flow path 19 Second water pipe row 20 Second water pipe

Claims (4)

  An annular first water pipe row 4 constituted by a plurality of first water pipes 3, 3,... And having a gap 5, 5,... Formed over a predetermined range between the adjacent first water pipes 3, and the first water pipe. A combustion chamber 9 formed inside the row 4, a wall member 11 provided outside the first water tube row 4, and a gas flow path 13 formed by the first water tube row 4 and the wall member 11. The water pipe boiler is characterized in that the flow passage cross-sectional area in the predetermined range in the gas flow passage 13 is set so as to suppress an increase in gas flow velocity.   An annular first water pipe row 4 constituted by a plurality of first water pipes 3, 3,... And having a gap 5, 5,... Formed over a predetermined range between the adjacent first water pipes 3, and the first water pipe. A combustion chamber 9 formed inside the row 4, a wall member 11 provided outside the first water tube row 4, and a gas flow path 13 formed by the first water tube row 4 and the wall member 11. A water pipe boiler characterized by gradually increasing the cross-sectional area of the predetermined range in the gas flow path 13 toward the downstream side in the gas flow direction.   3. The water tube boiler according to claim 1, wherein each gap 5 is made smaller as the gap 5 on the downstream side in the gas flow direction in the gas flow path 13. The water pipe boiler according to any one of claims 1 to 3, wherein the wall member 11 is an annular second water pipe row 19 constituted by a plurality of second water pipes 20, 20,.

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